JPH08329839A - Manufacture of shadow mask for color cathode-ray tube - Google Patents

Abstract

PURPOSE: To establish a manufacturing method for a shadow mask of such a structure that its phosphor layer or a matrix hole in a photo-absorbing layer of a phosphor screen is made circular, with which electron beam apertures are provided in a plate as a work for shadow mask using a specified process, by specifying the photo-mask, and forming electron beam aperture which is circular when viewed in the path direction of electron beam. CONSTITUTION: A photo-sensitive film 31 is formed on each surface of a plate 30 as a work for shadow mask, and the surfaces are subjected to exposure and development through the first and second photo-masks 45a, 45b which are provided with a major hole pattern and a minor hole pattern, and resist films 46a, 46b consisting of patterns corresponding to the photo-mask pattern are formed, followed by etching so that major holes 47 are provided in one surface while minor holes 48 are provided in the other. Thus electron beam apertures are formed, wherein the major hole pattern 51 for the first photo-mask 45a is made in peanut shape in the emitting direction of the photo-mask, and the minor hole pattern 52 for the second photo-mask 45b is made circular.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a shadow mask for a color cathode ray tube.

[0002]

2. Description of the Related Art In general, a color cathode ray tube has, as shown in FIG. 6, an envelope composed of a substantially rectangular panel 1 and a funnel-shaped funnel 2 integrally joined to the panel 1. Emit blue, green, and red light on the inner surface of panel 1 3
A phosphor screen 3 formed of a color phosphor layer is formed, and a substantially rectangular shadow mask 4 is arranged inside the phosphor screen 3 at a predetermined distance from the phosphor screen 3. The shadow mask 4 comprises a substantially rectangular mask body 5 and a substantially rectangular mask frame 6 attached to the peripheral portion of the mask body 5. A large number of electron beam passage holes are formed in a predetermined array pitch on the main surface portion of the mask body 5 facing the phosphor screen 3. On the other hand, in the neck 8 of the funnel 2, an electron gun 10 that emits the three electron beams 9 is arranged. Then, the three electron beams 9 emitted from the electron gun 10 are deflected by the horizontal and vertical deflection magnetic fields generated by the deflection device 11 mounted outside the funnel 2, and fluorescence is emitted through the electron beam passage holes of the shadow mask 4. The body screen 3 is horizontally and vertically scanned to form a structure for displaying a color image.

Among such color CRTs, particularly for color CRTs for displays used for displaying information in OA equipment and the like, the electron beam passage hole of the shadow mask 4 is formed in a circular shape, and the phosphor screen is correspondingly formed. As shown in FIG. 7, 3 is formed in a structure in which dot-shaped three-color phosphor layers 14B, 14G, 14R are provided so as to be embedded in the matrix holes of the matrix-shaped black light absorption layer 13. .

As shown in FIG. 8, the electron beam passage hole of the shadow mask is usually formed in the large hole 16 formed on one surface side facing the phosphor screen and on the other surface side (electron gun side). The small holes 17 communicated with each other, and the communication portion 18 has a communication hole having the smallest hole diameter.
The hole diameter and shape of 9 are substantially determined by the communicating portion 18 between the large hole 16 and the small hole 17, and in the shadow mask 4, the communicating portion 18 is circular.

By the way, as described above, the shadow mask 4
The color cathode ray tube having the circular electron beam passage hole 19 has a matrix hole of the light absorption layer 13 of the phosphor screen 3 (and the phosphor layers 14B, 1
There is a problem that 4G, 14R) does not become a perfect circle.

That is, in general, a phosphor screen of a color cathode ray tube is formed by a photographic printing method using a shadow mask as a photomask for forming a phosphor screen, and as one step, as shown in FIG. 9, it is applied to the inner surface of the panel 1. Light 23 emitted from a light source 22 arranged at a position corresponding to an electron gun of a color cathode ray tube passes through a shadow mask 4 on a phosphor screen forming coating film 21 such as a formed photosensitive film or photosensitive phosphor slurry layer. There is a step of baking the pattern corresponding to the electron beam passage hole of the shadow mask 4, and the matrix hole of the light absorption layer and the phosphor layer are formed in the baked part of the pattern. In FIG. 9, reference numeral 24 is a correction lens for approximating the trajectory of the light 23 emitted from the light source 22 to the trajectory of the electron beam emitted from the electron gun of the color cathode ray tube.
Reference numeral 5 is a correction filter for correcting the light amount distribution on the inner surface of the panel 1.

However, when a phosphor screen is formed by using the shadow mask 4 having a circular electron beam passage hole by the above method, the light 23 emitted from the light source 22 emits the electrons of the shadow mask 4 except in the center of the panel 1. It crosses the beam passage hole obliquely and reaches the inner surface of the panel 1. Therefore, the pattern corresponding to the electron beam passage hole of the shadow mask 4 projected on the phosphor screen forming coating 21 is
The matrix hole of the light absorption layer or the phosphor layer formed on the inner surface of the panel 1 is distorted into an elliptical shape having the minor axis in the radiation direction of the panel 1, and the matrix hole 2 of the light absorption layer is shown in FIG.
As shown in FIG. 7, the panel 1 has an elliptical shape having a minor axis in the radial direction, which deteriorates white uniformity, color purity, and the like.

In order to prevent the matrix hole 27 of the light absorption layer and the phosphor layer from becoming elliptical, the electron beam passage hole other than the center of the shadow mask 4 is formed into an elliptical shape having the major axis in the radiation direction of the shadow mask 4. However, it is difficult to manufacture such a shadow mask by the conventional technique.

That is, the electron beam passage hole of the conventional shadow mask is formed by the photoetching method, as shown in FIG.
As shown in FIG. 1, a photosensitive film 31 is applied and formed on both surfaces of the shadow mask material plate 30, and the photosensitive film 31 on one surface is
As shown in FIG. 12A, a first negative plate 33a (a first photomask for forming a shadow mask) on which a circular dot-shaped pattern 32a corresponding to the large hole 16 of the electron beam passage hole 19 shown in FIG. 8 is formed. Mask), on the photosensitive film 31 on the other surface,
A second negative plate 33 having a circular dot pattern corresponding to the small holes 17 of the electron beam passage hole 19 shown in FIG.
b (second photomask for shadow mask formation) is closely contacted and exposed, and the negative films 33a and 33b are formed on the photosensitive films 31 on both sides.
Patterns 32a and 32b are baked and developed to form a resist film consisting of patterns corresponding to the negative plates 33a and 33b on both surfaces of the shadow mask material plate 30.
Shadow mask material plate 30 on which this resist film is formed
Is formed by etching from both sides. In order to form an elliptical electron beam passage hole by this method, each pattern 32 of the first and second negative plates 33a and 33b is formed.
It suffices if a and 32b have an elliptical shape, but it is extremely difficult to form such a pattern.

[0010]

As described above, in the color cathode ray tube for display used for displaying information in OA equipment and the like, the electron beam passage hole of the shadow mask is formed in a circular shape, and the phosphor screen is correspondingly formed. Is formed in a structure in which the three-color phosphor layer is embedded in the matrix hole of the matrix light absorption layer.

However, in general, a phosphor screen of a color cathode ray tube is formed by a photographic printing method using a shadow mask as a photomask for forming a phosphor screen, and a fluorescent film such as a photosensitive film or a photosensitive phosphor slurry layer formed on the inner surface of the panel. When the body screen forming film is exposed through a shadow mask by light emitted from a light source arranged at a position corresponding to the electron gun of the color cathode ray tube, and a pattern corresponding to the electron beam passage hole of the shadow mask is baked, Except in the center of the panel, the light emitted from the light source is
Since it reaches the inner surface of the panel diagonally across the electron beam passage hole of the shadow mask, the pattern corresponding to the electron beam passage hole of the shadow mask projected on the phosphor screen forming film has a minor axis in the radiation direction of the panel. The problem is that the matrix hole of the light absorption layer and the phosphor layer formed on the inner surface of the panel become elliptical with the minor axis in the emission direction of the panel, which deteriorates white uniformity and color purity. There is.

In order to prevent the matrix hole of the light absorbing layer and the phosphor layer from becoming elliptical, the electron beam passage hole other than the center of the shadow mask may be formed into an elliptical shape having a major axis in the radiation direction of the shadow mask. However, it is difficult to manufacture such a shadow mask by the conventional technique.

The present invention has been made in view of the above problems, and the shadow mask is used as a photomask for forming a phosphor screen by a photoprinting method. Matrix holes in the matrix-shaped absorption layer of the phosphor screen and the fluorescence are formed. An object of the present invention is to obtain a method for manufacturing a shadow mask in which an electron beam passage hole of a shadow mask having a circular body layer can be easily made into a predetermined elliptical shape.

[0014]

Means for Solving the Problems A photosensitive film is formed on both sides of a shadow mask material plate, and the first photomask having a pattern for large holes and the pattern for small holes are formed on the photosensitive films on both sides. After exposing through a second photomask and developing to form a resist film having a pattern corresponding to the pattern of each photomask on each of the photosensitive films on both sides, the shadow mask material plate on which the resist film is formed is In the method for producing a shadow mask for a color cathode ray tube, which is formed by etching to form a large hole on one surface side of the shadow mask material plate and a small hole on the other surface side to form an electron beam passage hole, The pattern for large holes is made into a peanut shape obtained by shifting the center position of the circular dot in the radial direction of the photomask and striking it twice. The small hole patterns of the click is circular, these first and the shadow mask blank by using a second photo mask as viewed from the track direction of the electron beam so as to form the electron beam apertures that form a circle.

[0015]

When the first and second photomasks used for forming the electron beam passage holes of the shadow mask are constructed as described above, the large holes and the small holes that substantially determine the formation of the electron beam passage holes are formed. Since the shape of the communication part is largely controlled by the shape of the large hole, the electron beam passage hole is made an elliptical shape with the major axis in the radiation direction of the shadow mask when viewed from the direction perpendicular to the shadow mask material plate, and from the orbital direction of the electron beam. When viewed, it can be circular.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 1 shows a shadow mask according to the embodiment. This shadow mask is a phosphor screen in which dot-shaped phosphor layers emitting blue, green, and red are provided so as to be embedded in the matrix holes of the matrix-shaped black light absorption layer formed on the inner surface of the panel. The mask main body 42 has a large number of electron beam passage holes 41 formed in the main surface portion 40 facing each other, and a mask frame 43 attached to the peripheral portion of the mask main body 42.

As shown in FIG. 8, each electron beam passage hole 41 of the mask body 42 has a large hole formed on the side facing the phosphor screen and a small hole formed on the other side. Of the electron beam passage hole 41 of the mask main body 42.
Is substantially circular at the center of the mask body 41 when the communicating portion that determines the hole diameter and shape of the electron beam passage hole is viewed from the central axis (Z axis) (coincident with the tube axis) direction of the shadow mask. Other than the center, the shadow mask is formed in an elliptical shape having a major axis in the radial direction, emitted from an electron gun of a color CRT, and deflected by a deflecting device. When forming a phosphor screen by the method,
When viewed from the orbital direction of the light emitted from the light source (see FIG. 9)), the communicating portion is formed in a circular shape. 2A and 2B, the shape (circular shape) of the electron beam passage hole 41 at the center of the mask body 42 when viewed from the central axis direction of the shadow mask is shown in FIGS. The shape (elliptical) of the electron beam passage hole 41 at the end of the axis (H axis) is the same as (e) and (f), and the shape (elliptical) of the electron beam passage hole 41 at the end of the vertical axis (V axis).
(G) and (h) show the shape (elliptical shape) of the electron beam passage hole 41 at the end of the diagonal axis (D axis).

The electron beam passage hole 41 of such a shadow mask is formed by the photo-etching method like the conventional shadow mask.

That is, as shown in FIG. 3 (a), first, a photosensitizer containing, for example, milk caseinate and ammonium dichromate as main components is applied to both surfaces of the shadow mask material plate 30 and dried to form a photosensitive film. 31 is formed. Then, as shown in (b), a first negative plate 45a (first for shadow mask formation) described later is formed on the photosensitive film 31 on one surface thereof.
Photomask), the second negative plate 45b on the other photosensitive film 31.
Adhere (second photomask for shadow mask formation) closely,
The first and second negative plates 45a and 45b are exposed to light emitted from a light source 46 disposed in front of them, and the photosensitive films 31 on both sides are exposed with the patterns of the first and second negative plates 45a and 45b, respectively. . Next, the first and second negative plates 45
The photosensitive film 31 having the patterns a and 45b printed thereon is developed to remove the unexposed portion, and as shown in FIG. 7C, the negative plates 45a and 45b are formed on both surfaces of the shadow mask material plate 30.
Resist film 46 having a pattern corresponding to the pattern
a and 46b are formed. Next, as shown in (d),
The shadow mask material plate 30 on which the resist films 46a and 46b are formed is etched from both sides, and the large hole 47 and the other surface on which the resist film 46b is formed are formed from one surface side where the resist film 46a is formed. Small hole from the side 48
To form the electron beam passage hole 41 in which the large hole 47 and the small hole 48 communicate with each other. Next, the resist films 46a and 46b remaining on both surfaces of the shadow mask material plate 30 in which the electron beam passage holes 41 are formed are peeled off to form a flat flat mask 49 as shown in FIG. .

After that, the shadow mask is formed by pressing the flat mask 49 into a predetermined shape.
Further, it is manufactured by welding a mask frame separately formed on the periphery thereof.

Of the pair of negative plates 45a and 45b,
The large hole pattern of the first negative plate 45a is a circular pattern 51C in the center as shown in FIG. 4 (a), but the horizontal axis end, the vertical axis end, and the diagonal line are approached toward the periphery. As shown for the shaft end patterns 51H, 51V, 51D, the negative plate 45a has a peanut shape whose major axis is in the radial direction. On the other hand, the small hole pattern of the second negative plate 45b is, as shown in FIG.
A circular pattern 52 having a smaller diameter than the pattern of the first negative plate 45a is formed over the entire surface of the negative plate 45b. The pattern of the first and second negative plates 45a and 45b is shown in FIG. 5 when the negative plates 45a and 45b are properly superposed.
As shown in (a) to (d), the circular pattern 52 of the second negative plate 45b is formed so as to be coaxial, and the circular pattern 52 of the second negative plate 45b is different from the peanut-shaped pattern of the first negative plate 45a. Is formed so that the center of the circular pattern 52 of the second negative plate 45b coincides with the center of the peanut-shaped pattern in the major axis direction.

The negative plates 45a and 45b are formed by plotting circular dots having a predetermined diameter on a photographic plate by a photoplotter. Especially the first negative version 4
For 5a, the central circular pattern 51C is formed by plotting the circular dots once, but for the patterns other than the central one, the circular dots of the same diameter are shifted twice by a predetermined distance in the radial direction of the photographic plate. It is formed by The second negative plate 45b is formed by plotting circular dots having a predetermined diameter once over the entire surface of the photographic plate at a predetermined pitch.

By the way, although the circular pattern 51C is formed in the center as described above, the first negative plate 45a composed of a peanut-shaped pattern having a major axis in the radial direction of the negative plate and the negative plate of the negative plate as it approaches the peripheral portion. Over the entire surface
Using the second negative plate 45b consisting of the circular pattern 52,
When the electron beam passage hole 41 of the shadow mask is formed by the photo etching method, the large hole 47 of the electron beam passage hole 41 formed on one surface side of the shadow mask material 30 corresponding to the pattern of the first negative plate 45a is formed. , Fig. 2 (c)
As shown in (h) to (h), the shadow mask can be formed into an elliptical shape whose major axis is in the radial direction as it approaches the peripheral portion of the shadow mask. If the large hole 47 has an elliptical shape in this way, the shape of the communicating portion between the large hole 47 and the small hole 48 formed on the other surface side of the mask material 30 is largely controlled by the shape of the large hole 47. Also, the shape of this communicating portion is an elliptical shape whose major axis is the radial direction when viewed from the central axis direction of the shadow mask. Therefore, when the peanut-shaped pattern of the first negative plate 45a is formed, by shifting the radial direction of the photographic plate and plotting twice, the intervals of the circular dots are adjusted appropriately according to the position of the photographic plate, so that the electron gun of the color CRT can be operated. When viewed in the orbital direction of the electron beam emitted and deflected by the deflecting device, the communication portion of the electron beam passage hole 41 formed can be circular.

Then, as described above, the electron beam passage hole 41 is formed.
If the communication part of the is made circular when viewed from the direction of the orbit of the electron beam deflected by the deflecting device, generally, the orbit of the electron beam deflected by the deflecting device and the shadow mask are used as a photomask for a photo printing method. Since the orbits of the light emitted from the light source when forming the phosphor screen on the inner surface of the panel almost coincide with each other, the matrix holes of the matrix-shaped light absorption layer forming the phosphor screen and the matrix holes The three-color phosphor layer provided so as to be embedded in can be circular. As a result, it prevents the deterioration of white uniformity and color purity caused by the conventional matrix holes of the matrix-shaped light absorption layer being distorted in an elliptical shape in the radiation direction of the panel, and improves the quality of the image drawn on the phosphor screen. be able to.

In the peanut-shaped pattern of the first negative plate 45a, when the distance between two circular dots having the same diameter constituting the peanut-shaped pattern becomes equal to or larger than the radius of the circular dot, the communicating portion of the electron beam passage hole of the shadow mask is formed. Cannot be elliptical when viewed from the central axis direction of the shadow mask. Further, during the etching after forming the resist films 46 on both sides of the mask material 30, peeling of the resist films 46 easily causes hole defects. Therefore, especially when the distance between the two circular dots is 150% or more in terms of the eccentricity of the ellipse, it is better to plot another circular dot in the middle of the two circular dots. The part can be elliptical when viewed from the central axis direction of the shadow mask.

In the above embodiment, the patterns of the first and second negative plates were formed by plotting circular dots of the same diameter over the entire surface of the negative plate. However, the matrix-shaped light absorbing layer of the phosphor screen was formed. When making the matrix hole smaller from the center of the panel toward the periphery, the electron beam passage hole of the shadow mask must also be smaller from the center of the shadow mask toward the periphery. In order to form the passage holes, the patterns of the first and second negative plates also need to be made smaller from the center of the negative plate toward the periphery. Such a negative pattern is
It can be formed by making circular dots to be plotted when manufacturing a negative plate smaller from the center of the negative plate toward the periphery.

In the above embodiment, the color cathode ray tube in which the phosphor screen is composed of the matrix-shaped light absorption layer and the dot-shaped three-color phosphor layer provided so as to be embedded in the matrix hole has been described. The shadow mask according to the present invention can be applied to a color cathode ray tube in which the phosphor screen is composed of a three-color phosphor layer having no light absorption layer, and the three-color phosphor layer can be circular.

[0029]

EFFECTS OF THE INVENTION Photosensitive films are formed on both sides of a shadow mask material plate, and the first and second photomasks each having a large hole pattern are formed on the both sides of the photosensitive film. Through exposure and development to form a resist film having a pattern corresponding to the pattern of each photomask on both sides of the photosensitive film, and the shadow mask material plate on which this resist film is formed is etched from both sides In a method of manufacturing a shadow mask for a color cathode-ray tube in which a large hole is formed on one surface side of a plate-shaped member and a small hole is formed on the other surface side to form an electron beam passage hole, The center position of the circular dots is shifted in the radial direction of the mask to form a peanut shape obtained by striking twice, and the pattern for small holes of the second photomask is circular. , An elliptical shape of the electron beam apertures of the shadow mask viewed from the center axis direction of the shadow mask,
The electron beam emitted from the electron gun and deflected by the deflecting device can be formed into a circular shape when viewed from the orbital direction. As a result, the matrix holes in the matrix light absorption layer of the phosphor screen and the dot-shaped three-color phosphor can be made circular, and the matrix holes in the matrix light absorption layer and the phosphor screen can be elliptical in the radiation direction of the panel. It is possible to prevent the white uniformity and the deterioration of the color purity caused by the distorted shape and improve the quality of the image drawn on the phosphor screen.

[Brief description of drawings]

FIG. 1 (a) is a plan view showing the configuration of a shadow mask according to an embodiment of the present invention, and FIG. 1 (b) is a sectional view thereof.

FIG. 2 (a) is a view of the shape of an electron beam passage hole in the center of the mask body of the shadow mask seen from the direction of the central axis of the shadow mask, and FIG. 2 (b) is a horizontal axis sectional view thereof.
2 (c) is a view of the shape of the electron beam passage hole at the end of the horizontal axis as seen from the central axis direction of the shadow mask, FIG. 2 (d) is a sectional view of the horizontal axis, and FIG. 2 (e) is the end of the vertical axis. 2F is a view of the shape of the electron beam passage hole seen from the central axis direction of the shadow mask, FIG. 2F is a vertical cross-sectional view thereof, and FIG. 2G is a view of the shape of the electron beam passage hole at the end of the diagonal axis. FIG. 2H is a cross-sectional view taken along the diagonal axis of the mask as seen from the central axis direction.

FIG. 3A to FIG. 3E are views for explaining a method for manufacturing the shadow mask.

FIG. 4 (a) is a view showing a pattern of a first negative plate used in the above-mentioned shadow mask manufacturing method, and FIG. 4 (b).
FIG. 6B is also a diagram showing a pattern of the second negative plate.

5 (a) is a diagram showing a central pattern of the first and second negative plates, FIG. 5 (b) is a diagram showing a pattern of a horizontal axis end portion, and FIG. 5 (c) is a vertical axis. Figure showing the pattern of the end,
FIG. 5D is a diagram showing a pattern at the end of the diagonal axis.

FIG. 6 is a diagram showing a configuration of a color CRT.

FIG. 7 is a cross-sectional view showing the structure of a conventional phosphor screen of a color CRT.

FIG. 8 is a cross-sectional view showing a shape of an electron beam passage hole of a shadow mask of a conventional color CRT.

FIG. 9 is a diagram for explaining a method of forming the phosphor screen of the color CRT.

FIG. 10 is a diagram for explaining a problem of a conventional phosphor screen of a color CRT.

FIG. 11 is a diagram for explaining a conventional method for manufacturing a shadow mask for a color CRT.

FIG. 12 (a) is a diagram showing a pattern of a first negative plate used for forming an electron beam passage hole of a conventional shadow mask, and FIG. 12 (b) is a diagram showing a pattern of a second negative plate of the same. is there.

[Explanation of symbols]

 30 ... Shadow mask material plate 31 ... Photosensitive film 41 ... Electron beam passage hole 42 ... Mask body 43 ... Mask frame 45a ... First negative plate 45b ... Second negative plate 46a, 46b ... Resist film 47 ... Large hole 48 ... Small hole 51O, 51H, 51V, 51D ... Large hole pattern 52 ... Small hole pattern

Claims (2)

[Claims] 1. A first photomask on which a photosensitive film is formed on both surfaces of a shadow mask material plate, and the photosensitive films on both surfaces are respectively formed with a pattern for large holes and a second photomask with a pattern for small holes. After forming a resist film having a pattern corresponding to the pattern of each photomask on each of the photosensitive films on both sides by exposing and developing through, the shadow mask material plate on which the resist film is formed is etched from both sides. A method for manufacturing a shadow mask for a color cathode-ray tube, wherein a large hole is formed on one surface side of a leverage plate and a small hole is formed on the other surface side thereof to form an electron beam passage hole. The hole pattern is formed into a peanut shape obtained by displacing the center position of the circular dot in the radial direction of the photomask and striking the circular dot twice. A pattern having a circular small hole of a disk is circular, and by using these first and second photomasks, a circular electron beam passage hole is formed in the shadow mask material plate in a circular shape when viewed from the orbital direction of the electron beam. Method for manufacturing shadow mask for cathode ray tube. 2. A circular dot forming a large hole pattern is made smaller as it approaches the periphery from the center of the first photomask, and the hole diameter becomes smaller as it approaches the periphery from the center using this first photomask. The method of manufacturing a shadow mask for a color cathode ray tube according to claim 1, wherein the electron beam passage hole is formed.